Replacing IIS rewrite rules in web.config transform

As I didn’t have any rewrite rules in my main web.config, the Replace transform didn’t work. I successfully used the Insert transform, as below:

  <system.webServer>
<rewrite xdt:Transform="Insert">
  <rules>
    <rule name="CanonicalHostNameRule1">
      <match url="(.*)" />
      <conditions>
        <add input="{HTTP_HOST}" pattern="^www\.mysite\.com$" negate="true" />
      </conditions>
      <action type="Redirect" url="http://www.mysite.com/{R:1}" />
    </rule>
  </rules>
</rewrite>
</system.webServer>